We suggest developing a model system, which can be used to design an electrode capable of detecting specifically any peptide neurotransmitter in body fluids or tissues. An array of such electrodes will be able to detect several peptide neurotransmitters from the same site. The main principle of the suggested model is a cooperative interaction of the antibodies with different epitope specificity, immobilized on a functionalized conducting polymer matrix which has the appropriate morphology, with an antigen to be detected. The conducting polymer will possess a morphology, engineered to provide the highest surface area for such interaction. As a model antigen, we will use bovine serum albumin (BSA), and for the antibodies, we will use a pool of affinity purified polyclonal antibodies from a rabbit anti-serum. Simultaneous interaction of the two molecules of antibodies, chemically immobilized on the neighboring polymer chains, with one molecule of the antigen, will create a cross-link between the polymer chains, which will induce a measurable change in the conductivity of the matrix. PROPOSED COMMERCIAL APPLICATION: Not available.